Posts Tagged "Obesity"

A National Institutes of Health study found that non-invasive brain stimulation decreased calorie consumption and increased weight loss in adults who are obese. The findings suggest a possible intervention for obesity, when combined with healthy eating and exercise. Results were published in Obesity (link is external) concurrent with a presentation at the 2015 Obesity Society meeting.

Led by scientists at the Phoenix Epidemiology and Clinical Research Branch, part of NIH’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the team studied a total of nine men and women with obesity who resided in the Branch’s metabolic ward on two separate visits, each for eight days. On each visit, the participants ate a weight-maintaining diet for five days. Then for three days, they unknowingly received either active or sham (fake) transcranial direct current stimulation, or tDCS. Participants then ate and drank as much as they wanted from computerized vending machines. Applied to the scalp, the active tDCS targeted the brain region controlling behavior and reward.

The four people who got the sham stimulation during both visits consumed the same number of calories from the vending machines on each visit and did not lose weight. But the five people who got inactive stimulation on the first visit, and active tDCS at the brain target on the second visit, consumed an average of 700 fewer calories and lost an average of 0.8 pounds on the second visit.

Next, the researchers will compare a group getting only active tDCS with a separate group getting only sham stimulation. More study is needed to confirm the safety and effectiveness of tDCS for weight loss.

Source: NIH

Investigators working to unravel the impact of genetics versus environment on traits such as obesity may also need to consider a new factor: when individuals were born.

In the current issue of PNAS Early Edition a multi-institutional research team reports finding that the impact of a variant in the FTO gene that previous research has linked to obesity risk largely depends on birth year, with no correlation between gene variant and obesity in study participants born in earlier years and a far stronger correlation than previously reported for those born in later years.

“Looking at participants in the Framingham Heart Study, we found that the correlation between the best known obesity-associated gene variant and body mass index increased significantly as the year of birth of participants increased,” says Harvard Medical School instructor James Niels Rosenquist of the Massachusetts General Hospital (MGH) Department of Psychiatry, lead author of the report. “These results — to our knowledge the first of their kind — suggest that this and perhaps other correlations between gene variants and physical traits may vary significantly depending on when individuals were born, even for those born into the same families.”

The authors note that most studies of interactions between genes and the environment have looked at differences within specific birth cohorts —groups born during a particular span of years — which would not account for changes in the larger environment that take place over time. To investigate whether different conditions experienced by different age groups might alter the impact of a gene variant, they analyzed data from participants in the Framingham Offspring Study (which follows the children of participants in the original study) gathered between 1971, when participants ranged in age from 27 to 63, and 2008.

Source: Harvard Gazette

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Exposure to secondhand smoke and roadway traffic may be tied to increased body mass index in children and adolescents, a new study suggests.

Researchers studied 3,318 children in 12 Southern California communities beginning at an average age of 10, and then followed them through age 18. They used parental questionnaires to establish exposure to smoking, and data on traffic volume and levels of nitrogen dioxide, ozone and particulates to track pollution.

The study, in Environmental Health Perspectives, controlled for many other factors: sex, initial B.M.I., asthma, physical activity, insurance status, parental education and income, acres of parks and open space nearby, percentage of people living in poverty in each community.

But even after accounting for these issues and more, they found that compared with children exposed to no secondhand smoke or near-roadway air pollution, B.M.I. was 0.80 higher in children exposed to pollution alone, 0.85 higher in those exposed to secondhand smoke alone, and 2.15 higher in those exposed to both.

A normal B.M.I. for adults is 18.5 to 24.9. Higher than 25 is considered overweight, and above 30 obese.

“It would be interesting to know more about the mechanism,” said the lead author, Dr. Rob McConnell, a professor of preventive medicine at the University of Southern California. “But the finding challenges the view that obesity is due solely to increased caloric intake and reduced physical activity. That’s not the whole story.”

Source: New York Times

Sedentary lifestyle and not caloric intake may be to blame for increased obesity in the US, according to a new analysis of data from the National Health and Nutrition Examination Survey (NHANES). A study published in the American Journal of Medicine reveals that in the past 20 years there has been a sharp decrease in physical exercise and an increase in average body mass index (BMI), while caloric intake has remained steady. Investigators theorized that a nationwide drop in leisure-time physical activity, especially among young women, may be responsible for the upward trend in obesity rates.

By analyzing NHANES data from the last 20 years, researchers from Stanford University discovered that the number of US adult women who reported no physical activity jumped from 19.1% in 1994 to 51.7% in 2010. For men, the number increased from 11.4% in 1994 to 43.5% in 2010. During the period, average BMI has increased across the board, with the most dramatic rise found among young women ages 18-39.

“These changes have occurred in the context of substantial increases in the proportion of adults reporting no leisure-time physical activity, but in the absence of any significant population-level changes in average daily caloric intake,” explains lead investigator Uri Ladabaum, MD, MS, Associate Professor of Medicine (Gastroenterology and Hepatology), Stanford University School of Medicine. “At the population level, we found a significant association between the level of leisure-time physical activity, but not daily caloric intake, and the increases in both BMI and waist circumference.”

The study looked at the escalation of obesity in terms of both exercise and caloric intake. While investigators did not examine what types of foods were consumed, they did observe that total daily calorie, fat, carbohydrate, and protein consumption have not changed significantly over the last 20 years, yet the obesity rate among Americans is continuing to rise.

Researchers also tracked the rise in abdominal obesity, which is an independent indicator of mortality even among people with normal BMIs. Abdominal obesity is defined by waist circumference of 88 cm (34.65 in) or greater for women and 102 cm (40.16 in) or greater for men. Data showed that average waist circumference increased by 0.37% per year for women and 0.27% per year for men. Just like the rise in average BMIs, the group most affected by increased rates of abdominal obesity was women.

“The prevalence of abdominal obesity has increased among normal-weight women and overweight women and men,” observes Dr. Ladabaum. “It remains controversial whether overweight alone increases mortality risk, but the trends in abdominal obesity among the overweight are concerning in light of the risks associated with increased waist circumference independent of BMI.”

When Ladabaum et al grouped respondents to the most recent NHANES survey by race/ethnicity and age, they found that more than 50% of the workforce-aged adults in eight demographic subgroups reported no leisure-time physical activity. The following chart displays the results and highlights the differences between the 1994 survey results and those collected in 2010 (albeit, with slightly different survey methods). According to this data, women, and black and Mexican-American women in particular, showed the greatest decreases in reported exercise.

While increased caloric intake is often blamed for rising rates of obesity, no association between these was found in this study; in contrast, an association was found between the trends over time for lack of physical activity and high BMI numbers. “Our findings do not support the popular notion that the increase of obesity in the United States can be attributed primarily to sustained increase over time in the average daily caloric intake of Americans,” concludes Dr. Ladabaum. “Although the overall trends in obesity in the United States are well appreciated and obesity prevalence may be stabilizing, our analyses highlight troublesome trends in younger adults, in women, and in abdominal obesity prevalence, as well as persistent racial/ethnic disparities.”

There is no easy answer in our ongoing battle against obesity, but identifying the link between the drop in physical activity and increased BMIs, as well as the groups particularly affected, can assist public health officials to develop targeted, effective interventions. In an accompanying commentary Pamela Powers Hannley, MPH, Managing Editor, the American Journal of Medicine, notes, “If we as a country truly want to take control of our health and our health care costs, the Ladabaum et al paper should be our clarion call. From encouraging communities to provide safe places for physical activity to ensuring ample supply of healthy food to empowering Americans to take control of their health, we must launch a concerted comprehensive effort to control obesity.”

Strokes are increasingly hitting younger people–and the incidence of the crippling condition could double worldwide by 2030 according to the first global analysis of the problem. Though the chances of a stroke jump dramatically with age, the growing number of younger people with worrying risk factors such as bulging waistlines, diabetes and high blood pressure means they are becoming increasingly susceptible. Scientists combed through more than 100 studies from 1990 to 2010 studying stroke patients across the world and used modeling techniques when there wasn’t enough data. They found the incidence of stroke has jumped by a quarter in people aged 20 to 64, and that those patients make up almost one-third of the total number of strokes.

Most strokes occur when a clot blocks the blood supply to the brain. Patients often experience symptoms including a droopy face, the inability to lift their arms and garbled speech. If not treated quickly, patients can be left with long-term side effects, including speech and memory problems, paralysis and the loss of some vision.

Researchers said most strokes still occur in the elderly and that the numbers of people suffering strokes are still increasing as the world’s population ages.

Read more at CTV News.

A new UCSF-led study of nearly 3,000 individuals links obesity to the development of kidney disease. The work also shows that, when properly measured, declines in kidney function are detectable long before the emergence of other obesity-related diseases such as diabetes and high blood pressure. Healthy kidneys are vital to the proper functioning of the heart and brain, as well as the skeletal and immune systems, and the research adds additional urgency to the call for doctors to intervene early in life with obese patients, the researchers said. “We’re getting larger and larger at younger and younger ages, so the problems we will see that are directly related to obesity are going to become more common and they’re going to start earlier in life,” said Vanessa Grubbs, MD, UCSF assistant adjunct professor of medicine and first author of the new study. “Even before the level at which we can diagnose illnesses, decline in kidney function is happening. Is it reversible? We’re not sure. Preventable? It stands to reason that it would be.”

Source: University of California- San Francisco